[OpenLayers-Users] TileCache and KaMaps

[Christopher Schmidt]

On Tue, Dec 05, 2006 at 05:27:28PM -0500, Christopher Schmidt wrote:
> On Tue, Dec 05, 2006 at 03:55:28PM -0600, Tim Langlois wrote:
> > I know this was asked a while back by someone, but I could not find an
> > answer. What are the advantages/disadvantages to using TileCache vs.
> > KaMaps?  I am currently using KaMaps (via OpenLayers) to tile and cache
> > mapserver images on the backend.  It works well.  I wasn't sure if
> > moving to TileCache would improve performance and/or tile quality.  Has
> > anyone tried both?
> 
> TileCache was originally designed as a simple tile caching server. It
> didn't create larger images and split images up, one of the things that
> ka-Map does to work around limitations in MapServer. 
> 
> In 1.2, metaTiling support does exist in TileCache. It's not extremely
> well tested yet. It also doesn't hook directly into mapscript (and
> there aren't plans to, though it could in the future) to use added
> capabilities of MapServer like ka-map does. It also (due to lack of
> support in the Python Imaging library) doesn't support chopping up
> transparent tiles and maintaining transparency: this means that you
> can't metaTile transparent images.

After spending last night hacking with Schuyler, I'm now convinced that
TileCache supports transparency correctly, and that metaTiling is now of
a quality where I trust it. It doesn't do mapscript hacks to prevent
labelling in the metaBuffer area, but presuming a relatively small
metabuffer (and PARTIALS OFF, which doesn't cooperate well with ka-Map) 
the difference between ka-Map and TileCache behavior is probably
minimal, and the benefits of switching are, in my humble opinion,
significant.

I look forward to hearing any questions or concerns you have about
making a switch.

Regards,
-- 
Christopher Schmidt
MetaCarta